The global mobile communications industry is driving the need for improved cable entry devices for passing coaxial transmission line cable through planar obstacles. Effective bulkhead penetration is required at cellular ground base stations where installation usually requires feeding coaxial cable into a building or radio cabinet. However, the predominate cable entry devices now in use in wireless communications base stations generally perform poorly, are limited in their versatility, and are too expensive.
One important consideration for effective bulkhead penetration is to prevent moisture or other environmental elements from passing across the bulkhead. Moisture can migrate across the bulkhead at the boundary where the bulkhead meets the cable entry device, between device components, and at the interface of the cable and cable entry device. Various forces such as wind loading or shaking forces may occur in out-of-doors stations and give rise to vibrations which tend to loosen the cable entry device components and result in compromised leak resistance. For this reason, it is desirable for the cable entry device to provide a lasting leak-tight fit under all types of environmental conditions.
Another consideration is to provide a single cable entry device that is compatible with a variety of wall or bulkhead thicknesses. Frequently, bulkheads of various thicknesses are encountered during base station installation. For example, the cable entry device may be used with cabinet walls, shelter entry plates, roof and wall plates, grounding plates, and other similar thin-walled planar obstacles that a transmission line, cable, waveguide, or other member might need to penetrate. Installation is frustrated when some cable entry devices are unsuited for use with a particular bulkhead thickness. Since storing and/or stocking many different devices for use in various situations is uneconomical, it is desirable that the same cable entry device be compatible and function properly with a variety of bulkhead thicknesses.
Furthermore, increased ease of installation is desired especially since some cable entry devices are installed in very awkward locations. These circumstances, for example, include limited intimate access to one side of the bulkhead. Installation is further complicated by prior art devices having a multitude of component parts. For example, some prior art devices require a secondary mounting plate which is attached to the bulkhead with screws, nuts, and sealing compound. These devices require the installer to control many parts at the same time and sometimes necessitate the assistance of another worker.
Hence, in addition to accommodating multiple cables or members, multiple shaped members, or a combination of either, what is needed is a bulkhead penetrator which is leak tight, simple to install, compatible with a variety of bulkhead thicknesses, and economical to manufacture and distribute.